Research topics

Cataclysmic Variables (CVs) are compact, short period, interacting binaries with a white dwarf as the primary star. We are interested in populations studies and on the detailed physical interaction scenarios between the two stars in the binary. We use spectral and temporal information from X-ray missions like XMM-Newton and eROSITA to uncover new systems with mass transfer onto the compact stellar remnant and attempt an understanding of the physical mechanisms. The Milky Way Mapper project (MWM) in SDSS-V is instrumental to identify the complementary samples of compact white-dwarf binaries without mass transfer. The combination of all surveys will hold the key to solve the evolution of compact white-dward binaries.

Dust scattering halos can occur when the light from a distant X-ray source hits a dust layer on its way to Earth, e.g. in a spiral arm of our Milky Way. The light is then scattered, i.e. it is deflected from the original direction of propagation. If the background light source shines continuously, a more or less structureless nebula is formed. If the background light is short-lived, a flash light so to speak, a ring is formed as an echo of the scattering process. The scattered light covers a longer path than the directly emitted light. From the scattering geometry, distances to the light source and to the scattering medium can be determined with high precision.